Flat plate crossflow, flat plate counterflow, and cylindrical air-to-air heat exchangers are used to recover thermal energy from ventilation air that has been conditioned. Generally they operate on the outside air and are “preconditioners” upstream of heating and/or cooling coils that are used for thermal conditioning of the building supply air. When the plates are made of a material that is impervious to moisture they are generally referred to as heat recovery ventilators (HRV) that recover sensible energy. When the plates are made of a material that can transmit moisture they recover latent energy as well and are then generally known as energy recovery ventilators (ERV).
A new class of ERV devices use thin polymer films for plates. The polymer is chosen for excellent moisture (latent heat) transmission under the influence of a difference in the absolute concentration of water vapor on the two sides of the plate. These devices have been dubbed enhanced energy recovery ventilator (EERV) or membrane energy recovery ventilator (MERV) devices. An exemplary device is found in U.S. Pat. No. 6,684,943.
Exemplary devices use a stack of spaced-apart plates. With reference to exemplary square plates, between each two adjacent plates, a pair of closure bars is positioned along a pair of opposite edges to laterally enclose a channel between the plates. The pair of orientations may alternate to define two interspersed sets of channels: one set of the channels passing the heat/moisture donor air; and the other set of channels passing the heat/moisture receiving air.